Selector brush



June 28, 1949. G, DEAKlN 2,474,233

SELECTOR BRUSH Filed Feb. 25, 1945 url INVENTOR. GERALD DEAKIN B Yy y ENT Patented `lune 28, 1949 F ICE` (Cl. 20Min).

i-Claims. 1i'

My invention` relates to electricall contact brushes and moreparticularly; although noteX- clusively, to brushes for" selectorl switches for telecommunicationA4 systems:

An object of "the inventionds' to provic'i'e a contact brush compri-sing a springy member which is providedswitir a speciahbrushoi` brush shoe guide attached to butf insulated' from f the spring member, thus dispensing with` separate'v brush guides proposed' heretofore:

According to" certain` f eatures` of the invention, a contact brush conn'nises'-ak pair Qfgenerally parallel brushspringmembers xedto afsupporting means at-'one `endI and provided "adj acent the other end with i inwardly offsetvportions or shoes having contact surfaces-forwiping'overtlie con-v tact1 terminals or I' pins-fof i aJ'ba/nkf. Sue-h 'inwardly offset' portions' provide at`tiie outer faces ofthe springmemler, transverseL recesses over which are fixed lblocksI a orplates of E'insulatiifig material.

Guidesare attached toi saidi insulation blocks over said recesses andserve to i guide Athe spring membersalong av linef of terminal i Contact?. pins. These guides comprise inwardlyz and I rearwardly converging pvcln-ticms'` and ther'inner'` portions-are substa'n'tiallyy in -thef planes soffsaid'ishoesvibutf are spacedA therefrom ttius preserving. ther insulation of the guides from the springs. The-shoes are iiaredoutwardlyattheir edges :oppositeto those adj acent the effective,partsofsaid I guides.

The device of'thel present inventionihasfmany' advantages.: No. insulating material will.- rubon that'part'of the pin non .which .the brush shoe rides. The guide issadjac'entftozthefbrushashoe sorthat no inward l bending.. of :theffbrushshoe: will f cause thefinsulatorzinsteadiiofitheabrush shoe to rubor: the pins: Theashoezi willftrayei .1 from-i pinA toy pin withzno` orrvery'flittledrop betweenfpi-ns; thereby noti onlyxreducingfivibrationto minimum but also increasing? the-L useful rubbing surface to substantiallyf or" 90;:- per centr. of the; distances between the axes of adjacent pins:-

The above'.` and. otherr'featuresmvill. bet fully understood' from: consideration ofy thefollowing description of r oneembodiment` ot .myinvention taken, inf conjunction with-Y the` accompanying drawings-iinA which:

Fig; 1 .isafside `elevation-.oa a-brush junit;

Fig. 2v is van:elevation as seen from the right of lFig. 1;.

Fig.` Brisa viewfioi:the-structurerof` Fig. 1 as' Fig.l 6 isasection cnthelineeSr-Eioflig 4; and:`

Iable. material such as phosphorl bronze.

2 Fig: '7 is a section' taken on the-line 'i-'l of Fig; 4:

My inventionis disclosed'as applied to a flattype selector-switch4 of the `kind disclosed in 4Patent No: 2,330,8f12`is'suedtomelon October 5,v 1943.

Only one brush unit is illustrated in the accom" panyingv drawings;v but* it should" be lunderstood thatinpractice eig-htorany other suitable numu ber willbe mounted on'tlieA same'brush-carriage whichis moved fbacle and v'forth in areciprocatory manner' over the flat' terminal bank.

Referring to Figs. 1, 2; 3 and lithe brush unit comprises a strip I0 of suitable material-such as a laminated phenolic sheet adapted-to be secured to a brush carriage'in -anyvsuitable' manner. Securedlto saidstrip l0 by rivets or? eyelets Il are two phosphor-bronze' brushsprings` I2.V The upperv portions offthebrush springs il 2S are formed with' lateral* extensions I3Yv` forl wipingY along a feedrfb'ar (not shown);

The'freeends'v of the brush springs IZZareprovided 'i with laterally onv inwardly displaced parts constituting brush-shoes I4fhaving contactsuzw faces'- l 5 I atitheinnery sides thereof .i and 'adapted to wipeover contactpinsf I6' linearly arranged. These pinst may be: made of anhard metal v such as phosphorvbronzef.orstainlesssteel. At one edge each lbrush shoezlll is substantially in alignment with the edgesofthe! spring'above and below the brush shoe, but ati the oppositeedge of thef spring .there is yprovided'alwingicor guide l1 turned' outwardly,thereby providing: an opening daringr outwardly` from'the shoes'.l I4.. At .some distance above-shoesrlllgthez springs' I2 are provi'dedwith lugsior projections lvfwhich prevent the springs idf from touching :when their'brushes leave a pinlatfthe end' Iof a run or traverse. The inwardI movement-of the brushesrat the end of a run or stroke: is thus: reduced or'made, Very small. Asfa' resultthemovement ro'f'the brushes when vthe. endxpirris ret-engaged will be very small.

At the edges of the brush shoes lfremote from theigui'des' Il; provision isi-made of Ametallicguides i9 secured tothe brush 4springs: l2 but insulated therefrom; Theseguidesrlaarefmadeof any suit- The contact face of each of said springs is necessarily too-:short to contact'v twov pins I8- at the same time. and therefore al brush shoe might drop down"betweensuccessive' pins IE5,` Each guide Il provides a part ofwhichone face is in alignn mentfwith the Acorresponding contact surface so as` to lengthen thev effective supporting surface without changing the length of the'` effective contact surface, the guide being' insulated from the shoe. With such extended`4 supporting surface,

the brush may engage two successive pins I6 at one time although being in electrical contact with only one pin I6 at a time.

As illustrated, the insulating support for each guide I'I is provided by a block or plate 20 of insulating material such as laminated phenolic material, placed across the recess at the back of the shoe I4 and secured to the springs I2 by suitable means such as eyelets 2|. Each guide I'I may be made of a metallic strip preferably of phosphor bronze deformed to provide a flat body 22 secured to insulating plate 20 at its outer face by suitable means such as an eyelet 23, a flat portion 24 inclined inwardly and rearwardly from the outer edge of body 22 and a short ilat portion 25 extending rearwardly in alignment with shoe I4 but spaced therefrom. As indicated most clearly in Fig. 4, the insulating plate 20 is cut away to receive the downwardly and rearwardly extending part 24 of the guide I9.

As best shown in Fig. 7, a spring I2 will always be guided by at least one pin I6, even during the period when contact has been broken with one contact pin I6 and has not been established with the next pin.

It should be understood that while I have illustrated only one form of the invention and as applied to only one form of switch it is applicable in other forms and to other forms of apparatus without departingfrom the invention as defined by the appended claims.

I claim:

1. An electrical contact brush for a selector switch comprising a metallic spring member having a contact surface for successive engagement with a series of stationary terminals, a metallic guide member mounted on said spring member in alignment with said surface and spaced from the forward edge thereof in the direction of movement of said brush, means for electrically insulating said guide member from said spring, said contact surface being shorter in the direction of movement of said brush than the space between adjacent terminals and said guide member extending forwardly in the direction of movement of said brush to engage a terminal before said spring contact surface leaves the succeeding terminal, and means to urge said contact surface towards said terminal.

2. An electrical contact brush according to claim 1 wherein the metallic guide member has a forward surface inclined away from the plane of said contact surface to guide the advancing spring into position for said contact surface to engage the next stationary terminal.

3. The combination with a row of linearly mounted contact pins, of a contact brush movable therealong and comprising a pair of generally parallel metallic spring members engaging opposite sides of said row of pins and having inwardly offset contact portions adjacent corresponding free ends of said spring members, and metal guides for engagement with said pins, insulated from said springs but supported thereby at substantially the same level as said contact portions.

4. The combination according to claim 3 wherein the inwardly offset portions are spaced from the ends of said springs thus providing recesses at the outer faces of said springs, and wherein plates of insulating material are secured across said recesses and said guides are secured to such insulating plates.

5. An electrical contact brush comprising a metallic spring member having an electrical contact surface, supporting means for said spring member, and guiding means mounted on said spring member comprising a block of insulating material secured to said spring member at the side opposite to said contact face and a metallic guide secured to such insulating block and having a part substantially parallel to said contact surface and projecting'beyond the lateral edge of said spring member, an inclined part extending rearwardly and inwardly and an inner part extending rearwardly but spaced from the forward edge of said spring member.

6. The combination according to claim 5 wherein a portion of said spring member is offset to provide a transverse recess at one face and at the other face a projection with the contact surface, and the block of insulating material is secured to said spring member across said recess.

'7. An electrical contact brush for a selector switch comprising a metallic spring member having a contact surface for successive engagement with a series of stationary terminals and a metallic guide member mounted on said spring member and in alignment therewith but electrically insulated therefrom, said guide member comprising a strip having a part extending across the back of said spring opposite said contact surface and substantially in advance of said spring, a second part extending rearwardly and inwardly to the path of said inner face and a third part extending rearwardly with its inner surface substantially in the path of said contact surface.

8. The combination with a row of contact pins, of a contact brush for movement therealong and comprising a pair of generally parallel metallic spring members having adjacent to corresponding ends inner contact surfaces for making electrical contact with said contact pins, and means for guiding said spring members to effect engagement of said contact surfaces with said pins including for each spring member a metallic guide secured thereto but insulated therefrom and in alignment with said Contact surfaces, said metallic spring members being provided with opposed parts to prevent engagement of said contact surfaces when they are carried beyond a terminal contact pin.

9. The combination with a row of contact pins, of a contact brush for movement therealong and comprising a pair of generally parallel metallic spring members having adjacent to corresponding ends inner contact surfaces for making electrical contact with said contact pins, and means for guiding said spring members to effect engagement of said contact surfaces with said pins including for each spring member a metal guide secured thereto but insulated therefrom and in alignment with said contact surfaces, said metallic spring members being provided at their edges remote from said guides with outwardly flared interior surfaces.

l0. The combination with a row of contact pins, of a contact brush for movement therealong and comprising a pair of generally parallel metallic spring members having adjacent to corresponding ends inner contact surfaces for making electrical contact with said contact pins, and means for guiding said spring members to effect engagement of said contact surfaces with said pins including for each spring member a metal guide secured thereto but insulated therefrom and in alignment with said contact surfaces, said guiding means comprising at the outer face of each spring member an electrically insulating body secured thereto and each metal guide including a fiat portion secured to said insulating body and extending toward the next pin to be contacted, a second at portion inclined inwardly and rearwardly and a third flat portion extending rearwardly with its inner face in alignment with the corresponding Contact face but with its rear edge spaced from the edge of the adjacent spring member.

GERALD DEAKIN.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number 6 UNITED STATES PATENTS Name Date Hickman June 9, 1942 Van Inwagen Feb. 29, 1944 Barber May 2, 1944 FOREIGN PATENTS Country Date Australia Sept. 6, 1938 

